Jeffrey Kluger

It’s one of the worst-kept secrets of family life that all parents have a preferred son or daughter, and the rules for acknowledging it are the same everywhere: The favored kids recognize their status and keep quiet about it – the better to preserve the good thing they’ve got going and to keep their siblings off their back.

Spending $1 for a brand new house would feel very, very good. Spending $1,000 for a ham sandwich would feel very, very bad. Spending $19,000 for a small family car would feel, well, more or less right. But as with physical pain, fiscal pain can depend on the individual, and everyone has a different threshold.

At the root of the shy temperament is a deep fear of social judgment, one so severe it can sometimes be crippling. Introverted people don’t worry unduly about whether they’ll be found wanting, they just find too much socializing exhausting and would prefer either to be alone or in the company of a select few people.